The Task Force on Systemic Pesticides — an international group of independent scientists convened by the International
Union for Conservation of Nature — produced the world’s first comprehensive scientific assessment of the ecological effects of neonicotinoids in 2015. This landmark review, which considered more than 1,100 peer-reviewed studies, as well as data from manufacturers, identified clear evidence of harm to honeybees as well as to a large number of other beneficial species, including aquatic insects at the base of the food chain, soil arthropods such as earthworms, and common birds (by cascade effects).
In 2017, the Task Force updated its assessment to take into account hundreds of new peer-reviewed studies (published since 2014) on systemic insecticides in the environment and their ecological effects. The new assessment reveals broader impacts that reinforce the conclusions of the original 2015 review: neonics and fipronil represent a major worldwide threat to biodiversity and ecosystems/ecosystem services.
The 2017 update is now published in the scientific journal Environmental Science and Pollution Research in 3 parts.

Over the past decades, both wild and domesticated insect pollinators are in dramatic decline, which puts at stake the existence of species, ecosystem resilience and global food security. Globally, 87 of major food crops depend on animal pollination. Together these account for 35 % of the world food production volume. Pollinator mediated crops are indispensable for essential micronutrients in the human diet. Many ornamental plants as well as crops for fibre, fodder, biofuels, timber and phytopharmaceuticals also depend on insect pollinators. This article aims to map the current situation of pollinators worldwide, with a focus on the critical role of pollinators in the human food chain and ecosystem sustainability, their intrinsic and extrinsic value, as well as the causes of their declines and the interventions needed to conserve them, in order to develop an argument for the importance of conserving and restoring pollinator populations and diversity. The present pollinator crisis threatens global and local food security, can worsen the problems of hidden hunger, erodes ecosystem resilience, and can destabilise ecosystems that form our life support system. An integrated approach that simultaneously addresses the key drivers is needed. This includes creation and restoration of floral and nesting resources, a global phase out of prophylactic use of neonicotinoids and fipronil, improvement of test protocols in authorisation of agrochemicals, and restoration and maintenance of independence in regulatory science. The authors argue that an international treaty for global pollinator stewardship and pollinator ecosystem restoration should be initiated in order to systemically counteract the current crisis.

The Worldwide Integrated Assessment of the Impact of Systemic Pesticides on Biodiversity and Ecosystems (WIA) has examined over 800 scientific studies spanning the last five years, including industry sponsored ones. It is the single most comprehensive study of neonics ever undertaken, is peer reviewed, and published as free access so that the findings and the source material can be thoroughly examined by others.

Scientists urge transition to pollinator-friendly agriculture
Utrecht & Tokyo, 7 June 2013
Honeybee disorders and high colony losses have become global phenomena. An international team of scientist led by Utrecht University synthesized recent findings on the effects of neonicotinoid pesticides on bees. Scientists conclude that owing to their large scale prophylaxic use in agriculture, their high persistence in soil and water, and their uptake by plants and translocation to flowers, neonicotinoids put pollinator services at risk.

Press release Utrecht University - May 2, 2013
Insect numbers have been declining in recent years. Research by Utrecht University has found a link between the super insecticide imidacloprid and a decline in abundance of insects and other invertebrates in surface-water. Scientists are ringing international alarm bells. “Stricter standards alone are not enough. This insecticide is so harmful and remains in the environment for so long that an international ban is definitely warranted.”

EFSA scientists have identified a number of risks posed to bees by three neonicotinoid insecticides[1]. The Authority was asked by the European Commission to assess the risks associated with the use of clothianidin, imidacloprid and thiamethoxam as seed treatment or as granules, with particular regard to: their acute and chronic effects on bee colony survival and development; their effects on bee larvae and bee behaviour; and the risks posed by sub-lethal doses[2] of the three substances. In some cases EFSA was unable to finalise the assessments due to shortcomings in the available data.

Report finds systemic pesticides not as effective as once thought, cites pest resistance as key reason to end mass uses of the harmful substances.

Overview
A new study published in the academic journal Environmental Science and Pollution Research calls into question the value of neonicotinoid insecticides (“neonics”) in agriculture. The research, conducted by the international Task Force on Systemic Pesticides, reviews more than 200 studies on the performance of neonics in controlling a wide range of insect pests on agricultural crops worldwide, including corn, wheat and many types of fruits and vegetables, as well as the available alternatives.

The American Bird Conservancy (ABC) says preliminary results of a study it is conducting show that EPA is underestimating the aquatic toxicity to birds and other wildlife of the controversial neonicotinoid class of insecticides, adding pressure to the agency to more strictly regulate those products amid concerns over their pollinator risks.

"Based on . . . preliminary results, we have reason to believe that EPA has underestimated the aquatic toxicity of the entire class of neonicotinoid insecticides," Cynthia Palmer, pesticide programs manager at ABC, says in Nov. 14 comments to EPA regarding the agency's registration review dockets for two of the neonicotinoids -- acetamiprid and thiacloprid.

Abstract: Reported widespread declines of wild and managed insect pollinators have serious consequences for global ecosystem services and agricultural production1, 2, 3. Bees contribute approximately 80% of insect pollination, so it is important to understand and mitigate the causes of current declines in bee populations 4, 5, 6. Recent studies have implicated the role of pesticides in these declines, as exposure to these chemicals has been associated with changes in bee behaviour7, 8, 9, 10, 11 and reductions in colony queen production12. However, the key link between changes in individual behaviour and the consequent impact at the colony level has not been shown. Social bee colonies depend on the collective performance of many individual workers. Thus, although field-level pesticide concentrations can have subtle or sublethal effects at the individual level8, it is not known whether bee societies can buffer such effects or whether it results in a severe cumulative effect at the colony level. Furthermore, widespread agricultural intensification means that bees are exposed to numerous pesticides when foraging13, 14, 15, yet the possible combinatorial effects of pesticide exposure have rarely been investigated16, 17. Here we show that chronic exposure of bumblebees to two pesticides (neonicotinoid and pyrethroid) at concentrations that could approximate field-level exposure impairs natural foraging behaviour and increases worker mortality leading to significant reductions in brood development and colony success. We found that worker foraging performance, particularly pollen collecting efficiency, was significantly reduced with observed knock-on effects for forager recruitment, worker losses and overall worker productivity. Moreover, we provide evidence that combinatorial exposure to pesticides increases the propensity of colonies to fail.

By Toshiro Yamada, Kazuko Yamada and Naoki Wada, Jpn. J. Clin. Ecol. （Vol.21 No.1 2012)Abstract Recently it has become a serious problem that honeybees suddenly vanish in their colony, which is referred to as a colony collapse disorder（ CCD）. We have made it clear by the field experiments for about four months what effect neonicotinoid pesticides such as dinotefuran and clothianidin have on the occurrence of CCD. Eight colonies consisting of about ten-thousand honeybees in each colony were investigated under the practical beekeeping conditions in our apiary. In this study foods containing dinotefuran of 1 ppm to 10 ppm or clothianidin of 0.4 ppm to 4 ppm were fed into a beehive. Three levels of concentration were 10（ high-conc.）, 50（ middle-conc.） and 100 low-conc.） times lower than that in practical use. The changes of adult bees, brood and the pesticide intake in each colony were directly examined. They suggest that each colony with the pesticide administered collapses to nothing after passing through a state of CCD, the high-concentration pesticides seem to work as an acute toxicity and the low- and middle-concentration ones do as a chronic toxicity. CCD looks mysterious, but it is just one of situations where a colony dwindles to nothing. We have proposed a CCD occurrence mechanism based on our results.
The NMR spectral analyses of dinotefuran and clothianidin in aqueous solution give the speculations that both are thermally stable under the heating condition of 50 ℃ ×24 hours and dinotefuran is radiationally stable under the ultraviolet-irradiation condition of 310 nm×50 W/m2 but clothianidin is unstable.

Abstract: There has been recent interest in the threat to bees posed by the use of systemic insecticides. One concern is that systemic insecticides may translocate from the soil into pollen and nectar of plants, where they would be ingested by pollinators. This paper reports on the movement of two such systemic neonicotinoid insecticides, imidacloprid and thiamethoxam, into the pollen and nectar of flowers of squash (Cucurbita pepo cultivars “Multipik,” “Sunray” and “Bush Delicata”) when applied to soil by two methods: (1) sprayed into soil before seeding, or (2) applied through drip irrigation in a single treatment after transplant. All insecticide treatments were within labeled rates for these compounds. Pollen and nectar samples were analyzed using a standard extraction method widely used for pesticides (QuEChERS) and liquid chromatography mass spectrometric analysis. The concentrations found in nectar, 10±3 ppb (mean ± s.d) for imidacloprid and 11±6 ppb for thiamethoxam, are higher than concentrations of neonicotinoid insecticides in nectar of canola and sunflower grown from treated seed, and similar to those found in a recent study of neonicotinoids applied to pumpkins at transplant and through drip irrigation. The concentrations in pollen, 14±8 ppb for imidacloprid and 12±9 ppb for thiamethoxam, are higher than those found for seed treatments in most studies, but at the low end of the range found in the pumpkin study. Our concentrations fall into the range being investigated for sublethal effects on honey bees and bumble bees.

Abstract: Declines in pollinator colonies represent a worldwide concern. The widespread use of agricultural pesticides is recognized as a potential cause of these declines. Previous studies have examined the effects of neonicotinoid insecticides such as imidacloprid on pollinator colonies, but these investigations have mainly focused on adult honey bees. Native stingless bees (Hymenoptera: Apidae: Meliponinae) are key pollinators in neotropical areas and are threatened with extinction due to deforestation and pesticide use. Few studies have directly investigated the effects of pesticides on these pollinators. Furthermore, the existing impact studies did not address the issue of larval ingestion of contaminated pollen and nectar, which could potentially have dire consequences for the colony. Here, we assessed the effects of imidacloprid ingestion by stingless bee larvae on their survival, development, neuromorphology and adult walking behavior. Increasing doses of imidacloprid were added to the diet provided to individual worker larvae of the stingless bee Melipona quadrifasciata anthidioides throughout their development. Survival rates above 50% were only observed at insecticide doses lower than 0.0056 µg active ingredient (a.i.)/bee. No sublethal effect on body mass or developmental time was observed in the surviving insects, but the pesticide treatment negatively affected the development of mushroom bodies in the brain and impaired the walking behavior of newly emerged adult workers. Therefore, stingless bee larvae are particularly susceptible to imidacloprid, as it caused both high mortality and sublethal effects that impaired brain development and compromised mobility at the young adult stage. These findings demonstrate the lethal effects of imidacloprid on native stingless bees and provide evidence of novel serious sublethal effects that may compromise colony survival. The ecological and economic importance of neotropical stingless bees as pollinators, their susceptibility to insecticides and the vulnerability of their larvae to insecticide exposure emphasize the importance of studying these species.

Abstract: Bumble bees are important pollinators whose populations have declined over recent years, raising widespread concern. One conspicuous threat to bumble bees is their unintended exposure to trace residues of systemic neonicotinoid pesticides, such as imidacloprid, which are ingested when bees forage on the nectar and pollen of treated crops. However, the demographic consequences for bumble bees of exposure to dietary neonicotinoids have yet to be fully established. To determine whether environmentally realistic levels of imidacloprid are capable of making a demographic impact on bumble bees, we exposed queenless microcolonies of worker bumble bees, Bombus terrestris, to a range of dosages of dietary imidacloprid between zero and 125 μg/L and examined the effects on ovary development and fecundity. Microcolonies showed a dose-dependent decline in fecundity, with environmentally realistic dosages in the range of 1 μg/L capable of reducing brood production by one third. In contrast, ovary development was unimpaired by dietary imidacloprid except at the highest dosage. Imidacloprid reduced feeding on both syrup and pollen but, after controlling statistically for dosage, microcolonies that consumed more syrup and pollen produced more brood. We therefore speculate that the detrimental effects of imidacloprid on fecundity emerge principally from nutrient limitation imposed by the failure of individuals to feed. Our findings raise concern about the impact of neonicotinoids on wild bumble bee populations. However, we recognize that to fully evaluate impacts on wild colonies it will be necessary to establish the effect of dietary neonicotinoids on the fecundity of bumble bee queens.